注水泥循环温度影响因素探讨

循环温度的准确预测是保障固井作业安全和固井质量的重要影响因素之一。特别对深井而言，水泥浆性能对温度十分敏感，温度预测偏低5 ℃会严重缩短水泥浆可泵送时间，易引发固井事故，温度预测偏高会延长候凝时间，甚至可能发生超缓凝，水泥柱顶部十天以上都无强度，延误后续钻进作业。为保证施工安全，提高固井质量，根据井下传热特点及施工流程，建立了一种新的二维瞬态注水泥循环温度预测模型。研究结果表明：（1）固井前应多周循环钻井液，并适当提高循环排量，可以有效降低注水泥循环温度；（2）冬季最高循环温度低于夏季，尤其对浅井而言差别更加明显，冬季适当降低循环温度设计值不会影响安全泵注，而且能减小水泥浆体系设计难度；（3）深井温度系数高于浅井，井眼尺寸越大，循环温度越低。

Discussion on the Influence Factors of Cementing Circulating Temperature

The accurate prediction of circulating temperature is one of the important affecting factors of guaranteeing the cementing operation safety and cementing quality. Especially for the deep well,the slurry is highly sensitive to temperature. If the prediction difference of circulating temperature is negative 5 degrees lower,the pumpable time will sharply be reduced, which will cause cementing trouble. If the prediction of circulating temperature is higher than actual temperature,the waiting on cementing time will be prolonged,which will lead to abnormal retardation,that is to say the strength of the top of cement column would not have developed until 10 days later,which delays the subsequent drilling operation. In order to guarantee the cementing operation safety and cementing quality,a new two-dimension simulator has been proposed according to the underground heat transfer construction process. The results show:Circulating drilling fluid several times and increasing the pump rate will reduce circulating temperature,and the circulating maximal temperature in winter is lower than in summer, especially for shallow well. So suitably reducing the design temperature in winter could not affect the pump safety. Temperature coefficient in deep wells is higher than in shallow wells,and the circulating temperature is lower if the borehole size is bigger.